One of my two shep crosses is named Finnigan too! I named him after a character from a Canadian children's show that I used to watch a bizillion years ago. Oh my gosh!! I just realized that your cat's name (Casey) is the other character from the show 'Mr. Dress up' too!! LOL Guess you were a fan too!
Anyway, I'm wondering if Casey chose that spot because she felt that Finnigan could provide some protection for her from the child that was pestering her. Maybe you could buy one of those cave like beds for Casey and put it next to Finnigan's bed. That way Casey would feel safe and 'hidden' and also be next to Finnigan which maybe she wants to be? And then poor Finn could have his bed back. Or you could buy a second bed like the current one and put them together to make a double bed! Might eat up all the space in your livingroom though. lol